As for Labour, in order to blunt Tory accusations that a Prime Mininster Miliband would be in the SNP’s pocket, it says it would not do any deals with the Nationalists even if they do hold the balance at Westminister.

Insulting people or implying their votes can be disregarded if they are cast for the ‘wrong’ party is likely to alienate even many who voted “No” last autumn.

With next Thursday’s election highly unlikely to yield any party an overall majority, its messy aftermath will also bolster the factors making Scotland’s eventual independence more likely, whoever ends up in Downing St – be it Ed Miliband or David Cameron.

If Labour emerge as the largest party – the bookies’ current favourite scernario – it will almost certainly need the support of SNP MPs to survive in office.

So far Mr Miliband has ruled out any deals, largely to try neutralise Conservative accusations that he would be a hostage to the Scottish Nationalists.

He has rejected offers to join forces to keep David Cameron out of Downing Street from SNP leader, Nicola Sturgeon, who has proved a formidable campaigner and debater and – given she is an incumbent First Minister – has impressed by increasing her already considerable personal popularity ratings.

But if the choice lies between taking office and making concessions to the SNP, will Ed Miliband really risk passing on the opportunity to be Prime Minister and give Mr Cameron a chance to form a government?

Some commentators have argued SNP leader, Nicola Sturgeon, has weakened her leverage over Labour by ruling out supporting David Cameron.

However, if Mr Miliband refused any concessions, he would risk losing even more support in Scotland and he knows that to have a hope of winning a majority at Westminster ever again his party needs to win back its former voters there – especially in its old heartland in and around Glasgow.

As Scotland’s biggest city Glasgow – and its surrounding towns – has been the key to the tilt towards independence and the SNP’s current popularity there should not come as a surprise to anyone who knows anything about Scottish politics.

The Party has gradually been eroding Labour’s hold on the city for many years and last September it was one of the few areas where a majority voted for independence.

Many Labour voters were disgusted their party joined with the Conservatives to oppose independence and are in no mood to forgive so they have moved over to the SNP, which not only advocates independence, but is also a left of centre party opposing cuts to health and welfare spending – seemingly more sincerely than Labour.

This fundamental shift in the political landscape could take on the proportions of continental drift if a large cohort of SNP MPs is returned to Westminster and the main parties refuse to talk to them.

So how does this help moves to independence given Ms Sturgeon has said this election is not about getting a mandate for a second referendum?

One course would be to continue the momentum set since 1999 of the gradual accretion of more powers for the Scottish Parliament which – according to proposals agreed by all parties after the referendum – is about to gain more say over tax and spending.

If Holyrood were to end up with de facto control over all domestic affairs and show it could manage just fine, it would take away a lot of the risk that deterred many from opting for independence last September.

At that point, the SNP could turn to the Scottish people and say: “we run our own affairs anyway, so why not take the next step and become formally independent?” It is this approach I suspect has been the SNP’s long-term strategy all along.

The other possible route to independence could open up if the Conservatives are in a position to form another coalition or minority government and it is not Ed Miliband moving into No 10, but David Cameron staying put.

This means there will be a referendum on whether the UK should leave the EU in 2017 – or even sooner if Mr Cameron has to do a deal with UKIP to stay in power.

If the result of this vote were to be to leave, but a majority of Scots had elected to stay in, the SNP is likely to argue that justifies another referendum on Scottish independence.

Nicola Sturgeon has already called on the other parties to agree that any decision to leave the EU would need to be endorsed by a majority in all four constituent nations of the UK. The Conservatives are not likely to agree to that, but would also find it hard to oppose another vote on independence if a majority of Scots had opted to stay in the EU.

Scotland has been the bright spot in a generally dull election campaign, but the result is going to be another thing altogether – we are in for a fascinating ride over the next few weeks.

The deals and decisions made – and not made – are very likely to carry us closer to the dissolution of the UK.

Alistair Burnett

Alistair Burnett is a journalist and analyst with 25 years of experience in BBC News. From 2004-2014, he was Editor of The World Tonight on BBC Radio 4 and before that was Editor of Newshour on BBC World Service. He has a particular interest in international relations and the implications of the shifting power relations in the world which are challenging the traditional western dominance of global affairs.